Organ culture of adult Rat and mouse tracheal epithelium: I. Ultrastructure following various culture periods

Summary Electron microscopic studies of adult rat and mouse tracheal epithelium maintained in organ culture for a period of up to 6 days were performed. In specimens cultured for 60 minutes no conspicuous micromorphological alterations could be observed. Following culture periods from 1–6 days the number of cilia in some of the ciliated cells was reduced while their structure and the other ultrastructural details of the epithelial cells were preserved. In specimens cultured for 5–6 days some additional alterations could be noticed: polymorphism of mitochondria, increased number of lysosomes, appearance of intracellular vacuoles, exhaustion of goblet cells and disappearance of granulated mast-cell like cells in the rat tracheal epithelium.I want to thank Miss J. Selbmann and Mrs. S. Kolassa for technical help and Mr. H. Wagner for preparing the micrographs; I am indebted to Dr. D. Kerjaschki and to Mr. H. Hörandner for performing preparations for scanning electron microscopy and to Mr. P. Scholze (Österreichische Studiengesellschaft für Atomenergie, Institut für Metallurgie, Abteilung Fremdkörperphysik) for preparing the scanning electron micrograph.This work was supported by the Fond zur Förderung der wissenschaftlichen Forschung: Project 2099.This paper is dedicated to Prof. Bargmann on the occasion of his 70th birthday.The author wishes to express her appreciation to Prof. Stockinger for suggestion and advice.     

Is it advantageous for Atlantic salmon to be triploid at lower temperatures?

Marine organisms living at low temperatures tend to have larger genomes and larger cells which suggest that these traits can be beneficial in colder environments. In fish, triploidy (three complete sets of chromosomes) can be induced experimentally following fertilization, which provides a model system to investigate the hypothesis that larger cells and genomes offers a physiological advantage at low temperatures. We tested this hypothesis by measuring metabolic rates and swimming performance of diploid and triploid Atlantic salmon (Salmo salar) post smolts acclimated to 3 or 10.5 °C. At 10.5 °C, triploids had significantly lower maximum metabolic rates which resulted in a lower aerobic scope compared to diploids. In addition, triploids initiated ram ventilation at lower swimming speeds, providing further evidence of a reduced capacity to meet oxygen demands during strenuous activity at 10.5 °C. However, at 3 °C, metabolic rates and critical swimming speeds were similar between both ploidies, and as expected substantially lower than at 10.5 °C. Therefore, triploidy in colder environments did not provide any advantage over diploidy in terms of metabolic rate traits or swimming performance in Atlantic salmon. We therefore conclude that traits, other than aerobic scope and swimming performance, contribute to the trend for increased cell and genome size in marine ectotherms living in cold environments.     

Essential roles for the Dhr78 orphan nuclear receptor during molting of the Drosophila tracheal system

The Drosophila Dhr78 orphan nuclear receptor has been proposed to play a role in molting of the tracheal cuticle and regulate gene expression during the third larval instar, possibly in response to a novel systemic hormonal signal. Here, we show that there are no essential maternal functions for Dhr78 during development, and that mutants missing both maternal and zygotic Dhr78 function die primarily during second and third instar larval development. We show that defects in the tracheal system can be observed as early as the first instar, manifested as regions of fluid in the dorsal tracheal trunks. In addition, Dhr78 mutant tracheae show a highly penetrant defect in gas filling at the first-to-second instar larval molt. Dhr78 expression in only the tracheal system is sufficient to rescue the lethality of Dhr78 mutants, and selective inactivation of Dhr78 function in the tracheae by targeted RNAi is sufficient to result in tracheal defects. Finally, we see no evidence for widespread activation of the Dhr78 ligand binding domain in third instar larvae using the GAL4-LBD system, arguing against a systemic hormone for the receptor at this stage in development. Taken together, our results indicate that Dhr78 exerts its essential functions during molting of the tracheal cuticle in Drosophila.     

Why Baja? A bioenergetic model for comparing metabolic rates and thermoregulatory costs of gray whale calves (Eschrichtius robustus)

A bioenergetic model is developed from empirically derived equations of morphometric, ventilatory and thermoregulatory variables to compare estimated field metabolic rates (FMR) of gray whale calves to estimates of unregulated body heat losses and consequent required thermogenesis at birth, natal lagoon departure, and weaning. Estimates of FMR are based on rates of oxygen consumption. Body surface and ventilatory heat fluxes are evaluated separately, then combined to estimate minimum total heat losses from birth to weaning at three ambient water temperature regimes typical of winter natal lagoons and Oregon coastal waters and arctic conditions during summer. Modeled heat losses of neonates in winter lagoons are half their estimated mean FMR. Neonates in good body condition appear to be capable of tolerating heat losses experienced in 10°C water without additional thermogenic activities above their estimated resting metabolic rates. This study provides new evidence that no thermoregulatory advantage accrues to neonates or to their mothers by being born in warm winter natal lagoons or by remaining there several weeks longer than other gray whales. Consequently, avoidance or reduced risk of killer whale predation seems a more likely candidate than reduced heat loss as the principal fitness benefit of low-latitude winter migrations.     

东莨菪碱抑制呼吸效应及其机制

本文给兔侧脑室、犬椎动脉以及静脉注射东莨菪碱，从呼吸频率、潮气量、通气量及血气分析多项指标皆观察到东莨菪碱有明显抑制作用，且存在剂量依赖关系。东茛菪碱尚能拮抗毛果靶香碱的呼吸效应，但不能拮抗６β－乙酰氧基去甲托烷呼吸抑制效庆，反而起协同作用。上述结果提示示东莨菪碱引起呼吸抑制可能与民呼吸中枢Ｍ１受体有关。     

Changes in Ventilation and Locomotion of Gammarus pulex (Crustacea,Amphipoda) in Response to Low Concentrations of Pharmaceuticals

Exposure to contaminants below lethal concentrations may affect the performance of organisms, resulting in measurable differences in behavior. We measured the response of the benthic invertebrate Gammarus pulex (Crustacea, Amphipoda) to sublethal concentrations of three pharmaceuticals, fluoxetine, ibuprofen and carbamazepine, and the cationic surfactant cetyltrimethylammonium bromide (CTAB). Responses in behavior during exposure were analyzed using the multivariate method of Principal Response Curves (PRC). The PRC results show that exposure to low pharmaceutical concentrations (range 1–100 ng/l) resulted in increased ventilation, whereas exposure to control or to high concentrations (1 μ g/l–1 mg/L) resulted in increased locomotion. Exposure to CTAB resulted in decreased locomotion and increased ventilation at increasing concentrations. The results of our experiments indicate that increased ventilation can be used as a general sign of stress, but not necessarily an early warning signal for mortality.     

Indoor Air Quality in Schools and Health Symptoms among Portuguese Teachers

The purpose of this study was: (i) to characterize the school indoor environment; (ii) to evaluate self-reported prevalence of disease symptoms among Portuguese teachers; and (iii) to evaluate, as far as we know for the first time in Portugal, the impact of the indoor air quality of schools on the prevalence of disease symptoms among teachers. The study was performed in the city of Oporto, starting in 2004; it included the analysis of questionnaires fulfilled by schoolteachers (n = 177), walkthrough surveys of schools grounds, buildings, and individual classrooms (n = 76), as well as indoor air monitoring. Respirable particle increase was related to chalk use and CO₂ concentrations widely exceeded reference values. Schools located near traffic lines presented higher benzene and toluene concentrations. The guideline for total viable microorganism concentration was exceeded in 35.6% of classrooms. Significant increases in disease symptoms among teachers could be related to poor indoor air quality, which was mainly due to inefficient ventilation and influence of traffic emissions. Statistically significant correlations were found between central nervous system injuries and the levels of CO₂ and total volatile organic compounds, and between upper respiratory problems and mucosal irritation and the levels of TVOC and respirable particles.     

Adaptations of fish species to oxygen depletion in a central Amazonian floodplain lake

Pronounced seasonal and daily oxygen concentration changes are characteristic for Amazonian floodplain lakes. Studies on the fish fauna of the Lago Camaleão, Solimões River, Amazonas, Brazil, showed several fish species which are able to survive prolonged periods of heavy hypoxia. Twenty species belonging to eight families were observed in the laboratory in order to determine their respiratory adaptations to hypoxic conditions and oxygen concentrations at which the fish present respiratory adaptations. Finally, the fish species were distributed throughout the habitats of Lake Camaleão according to their adaptation responses. Ten fish species used the surface water for aquatic surface respiration, four species used atmospheric oxygen for aerial respiration, four species used oxygen supplied by the exudation of the roots of floating macrophytes and two exhibited a high tolerance to hypoxic conditions, and well-developed physiological biochemical mechanisms. The fish fauna is well adapted to low oxygen concentrations. The large variety of morpho-anatomical adaptations associated with biochemical and physiological mechanisms to tolerate hypoxic and anoxic conditions enable the 20 fish species to exploit several habitats of Lago Camaleão, such as floating aquatic macrophyte meadows, open water and near the shoreline.